Congreso Internacional Arqueología Experimental Burgos 2014, 8-11 mayo

Reproducing Cato: An Experimental Approach To A Sulphur Mixture

Claudia Speciale, PhD Student, Università del Salento

Luca Zambito, PhD, Università di Messina

Sulphur is a very useful mineral for many applications. It burns easily, making a bluish light. Maybe for this reason, making a light at the same time hot and ╉cold╊, people used this mineral from the Bronze Age in

ceremonies of purification.

The author of Iliad and Odyssey speaks about it. When Achilles wants to celebrate Patroclos’ funeral, he purifies the area with sulphur. The same does Ulysses after killing the Proci. Another application of sulphur,

documented between the V BC and the V A.D. c., is in the manufacture of weapons. Sulphur is one of the most

important ingredients of fire mixtures used to burn siege machines. And also to create incendiary grenades.

Sicily, and in particular the area surrounding Agrigento, was one of the main sites of sulphur extraction. This

helped to build strong relationships with Rome and other agricultural centers in the Mediterranean Sea.

Among the historical sources and archaeological evidence, it is important to mention the Tabulae sulphuris

which, regarding the sulfur exploitation, exclusively refer to the Agrigento’s area. These inscriptions,

impressed on sulphur ingots, were related to the taxation and trade of the mineral.

The idea of this first generation experiment/experience was born reading Marcus Porcius Cato, that writes ╉de Agri cultura╊ in な6ど BC c.; he says about a mixture used on the grape plants to defeat an insect.

Sulphur is used even today, for its fungicide properties, but Cato is the first ancient source that writes about

it. As long as sulphur is involved, Luca Zambito wanted to experimentally answer a question: how much

sulphur do you need to protect a vineyard during the Republican era? Cato specifies the measures for every

ingredient, the procedure to cook the mixture and he gives some advices about HOW spread the mixture on

the plant when it is cool.

Following Cato’s recipe, if we consider congius as basic unit of measurement, we obtain about 8 liters and a

half of mixture. As first attempt, we decided to obtain only a quarter of it, easier to prepare and to manage.

Interpretation of the word ╉convolvolus╊, the insect to fight, is not unambiguous: it could be any kind of

grape leaffolders with their caterpillars; or something (a phytofagus insect, leaf-eater) similar to the well

known phylloxera (coming from North America in the 19th c.) or even a fungal disease (for example the

Anthracose, that Teophrastus describes); finally, it could be also a coleoptera such as Byctiscus betulae, an insect that involves into a leaf. And unfortunately, we don’t have any information from the ancient sources about convolvolus seasonality, and then if there were specific moment of the year to protect the plants.

Sulphur is often together with bitumen and pitch. Bitumen can be found in several Mediterranean sites.

Solino and Plinius testify its presence near Agrigento and explain to collect it using reed inflorescences. We

collected bitumen in two sites at about 30 km from Agrigento. First One is Grotta Bonura, a karst cave in the

gessoso-solfifero deposit, about 3 km north east from Cattolica Eraclea. In an area significantly called Valanghe dell’Oglio (literally oil valanche) we found bitumen.

The other site we went to is Madonna dell’Olio, in the territory of Bivona where there is an outcropping of

bitumen. During the collection process, we noticed that the amount of the hydrocarbon increases during the

summer, when the creek is dry and bitumen is not trailed by water; this hypothesis was confirmed by the

peasants who live there and let us think about a specific gathering season.

We made everything open-air, as Cato recommends, because of the unhealthiness of the smoke and the

explosive potential of the mixture. We took 1,5 l of Oil mixed to sludge (oil deposit) and cooked it on fire in a

metal pot for about one hour and a half; then we added about 200 ml of sulphur powder and 250 ml of

natural bitumen; after another hour and a half, the mixture reached a glue consistence, as Cato prescribed.

Letting it cool for about two hours (external temperature 18°, quite windy), it was ready to be used.

We didn’t calculate exactly the final amount, but it was less than 1 liter (the heaviest part of bitumen was at

the bottom of the pot).The mixture was enough to be spread on the branches of 6 plants of a modern

vineyard, each one with 4 branches of 60-70 cm. We used a homemade palm brush.

If we consider the total amount of the mixture, with 8,5 liters we could spread 24 plants. This is the first experience and of course we’re planning to repeat it to have more reliable conclusions. Not counting all the ╉personal╊ and unvaluable variables (such as the humidity and the atmosphere

temperature, the approximation of every peasant in the making of the mixture, the ability of the spreader, etc.), we can’t nevertheless ignore all the possible elements that affected our first attempt and that must be

evaluated for the next experiences to have a more and more reliable esteem of the sulphur amount:

- The ╉interpretation╊ of the measures, as we considered everything in proportion to the congius

- The repetition of the application (Only once? Only when the peasant noticed the disease? Once per year?

More than once per year?)

- Different ways of cultivation and pruning, depending on the plant, the agricultural traditions, the latitude,

etc.

- The possible misinterpretation of the spreading method (it is not totally clear if the trunk had to be oiled as

well, even if it looks unlikely)

- The vineyard density (how many plants in one area?)

As first result, we can say that 1 kg of sulphur was enough for about 25-30 plants. It’s then quite evident that the request of sulphur had to be very consistent, especially from the areas with the higher wine production.

Columella in I c. AD writes about having more or less 1000 plants per hectare, then we should calculate 240-

250 kg of sulphur per 1 hectare of vineyard. It means that the request for sulphur (and for bitumen as well)

had to be elevated, more than we could imagine through the almost invisible archaeological evidence. However, it’s important to underline that the collection of these materials was limited to very few

geographical areas. We should then analyze their historical development considering this specific point of

view and their fundamental role in sulphur and bitumen catchment and commerce from republican era until

III c. AD.

Reproducing Cato: An Experimental Approach To A Sulphur Mixture

Claudia Speciale, PhD Student, Università del Salento Luca Zambito, PhD, Università di Messina

Sulphur

Reproducing Cato: An Experimental Approach To A Sulphur Mixture

National Geographic, Java

"Vaso", the earliest illustration of a European cannon, /1327, Wikimedia

Mines, beginning 20th century

Sulphur and bitumen in Sicily

Reproducing Cato: An Experimental Approach To A Sulphur Mixture

Cato Cato, De agri cultura, 95

Convolvolus in vinia ne sit. Amurcam condito, puram bene facito, in vas aheneum indito congios II. Postea igni leni coquito, rudicula agitato

crebro usque adeo, dum fiat tam crassum quam mel. Postea sumito bituminis tertiarium et sulpuris quartarium. Conterito in mortario

seorsum utrumque. Postea infriato quam minutissime in amurcam caldam et simul rudicula misceto et denuo coquito sub dio caelo. Nam

si in tecto coquas, cum bitumen et sulpur additum est, excandescet. Ubi erit tam crassum quam viscum, sinito frigescat. Hoc vitem circum

caput et sub brachia unguito; convolvus non nascetur.

To keep convolvolus off the vines: Strain stored amurca and pour two congii into a

copper vessel; heat over a gentle fire, stirring constantly with a stick until it reaches

the consistency of honey. Take one-third sextarius of bitumen, and one-fourth

sextarius of sulphur, pulverize each in a mortar separately, and add in very small

quantities to the warm amurca, at the same time stirring with a stick, and let it boil

again in the open; for if you boil it under cover it will blaze up when the mixture of

bitumen and sulphur is added. When it reaches the consistency of glue let it cool.

Apply this around the trunk and under the branches, and convolvolus will not appear.

Reproducing Cato: An Experimental Approach To A Sulphur Mixture

Cato Cato, De agri cultura, 95

Convolvolus in vinia ne sit. Amurcam condito, puram bene facito, in

vas aheneum indito congios II. Postea igni leni coquito, rudicula

agitato crebro usque adeo, dum fiat tam crassum quam mel. Postea

sumito bituminis tertiarium et sulpuris quartarium. Conterito in

mortario seorsum utrumque. Postea infriato quam minutissime in

amurcam caldam et simul rudicula misceto et denuo coquito sub dio

caelo. Nam si in tecto coquas, cum bitumen et sulpur additum est,

excandescet. Ubi erit tam crassum quam viscum, sinito frigescat.

Hoc vitem circum caput et sub brachia unguito; convolvus non

nascetur.

Reproducing Cato: An Experimental Approach To A Sulphur Mixture

2 congios Oil sludge

6,56 l

1 tertiarius Bitumen

1,09 l

1 quartarius Sulphur

0,82 l

8,47 l mixture

What is convolvolus ?

Reproducing Cato: An Experimental Approach To A Sulphur Mixture

Lepydoptera caterpillars

Daktulosphaira vitifoliae (Phylloxera)

Anthracnose

Anthracnose

SEASONALITY?

Bitumen collection

Reproducing Cato: An Experimental Approach To A Sulphur Mixture

Cattolica Eraclea, Grotta Bonura

Mixture preparation

Reproducing Cato: An Experimental Approach To A Sulphur Mixture

Sulphur Powder 200 g

Oil/oil sludge 1,5 l

Bitumen 250g

Use of the Mixture

Reproducing Cato: An Experimental Approach To A Sulphur Mixture

¼ of Cato recipe for 6 grapes (every trunk 4 branches)

Use of the Mixture

Reproducing Cato: An Experimental Approach To A Sulphur Mixture

Results and perspectives

Reproducing Cato: An Experimental Approach To A Sulphur Mixture

- Different interpretation of the Measures - How many times per year? - Different ways of cultivation and pruning - Misinterpretation of the application method - Vineyard density

1 kg sulphur = about 25 plants

High request by wine production areas Growing esponentially from I c. AD

Columella, ab. 1000 plants x ha

251 kg sulphur x ha

Thanks to

Claudia Speciale, PhD Student, Università del Salento, claudiaspeciale@gmail.com Luca Zambito, PhD, Università di Messina, zambil@katamail.com

Mario Indelicato Damiano Greta&Ester Antonio Mandragora